[2] Petersen grew up in San Jose and attended Saint Francis High School.
[5] After one year at West Valley, Petersen transferred to Riverside City College, playing one game in the 2014 season, for 1+1⁄3 innings pitched, two strikeouts, and no runs allowed.
[8][1] While rehabbing from his injury, he made only one appearance in 2022 (in the Arizona Complex League)[1] before splitting the 2023 season between the Double-A Hartford Yard Goats and Triple-A Albuquerque Isotopes, with a combined 41 games and 4.10 ERA.
[1][9] Petersen signed a minor league contract with the Los Angeles Dodgers on January 24, 2024 and began the season with the Triple-A Oklahoma City Baseball Club.
[10] He made his MLB debut two days later against the Rockies, allowing one run on one hit and one walk while striking out two in two innings to pick up the win.